Field of Invention
The invention relates to a method and a system for monitoring an individual blade adjustment of a wind turbine which comprises a tower, a rotor which is arranged on the tower and has at least two rotor blades whose blade angle can be adjusted individually, and a blade adjustment system, wherein the blade adjustment system comprises a blade controller and sensors for sensing individual actual blade angles of the at least two rotor blades, wherein an individual blade controller is included which receives a collective set point blade angle from the blade controller and which actuates at least two rotor blades with respectively individual set point blade angles, as well as a corresponding wind turbine.
Brief Description of Related Art
Wind turbines with power regulation by adjusting the rotor blades have devices which monitor the correct position of the individual rotor blades for, inter alia, symmetry and error deviation. In addition, it is necessary to detect faults such as, for example, the uncontrolled and random adjustment of one or more rotor blades. In regulating concepts with individual blade adjustment, that is to say independent adjustment of the individual rotor blades, large asymmetries are intentionally generated. This makes particular demands of the monitoring of the individual blade adjustment.
For this purpose, the set point values of the blade angles are usually monitored as a manipulated variable and the actual values are monitored as measured values of the usually two or three, and in the case of relatively small systems even more, individual rotor blade angles for deviations. Furthermore, the asymmetries are monitored by comparing the individual actual values of the individual blade angles for deviations from one another. Finally, absolute limits of the rotor blade angles, usually minimal values, are monitored for upward transgressions. These monitoring operations bring about deactivation of the wind turbine when triggering occurs.
Particularly for large offshore systems or in the case of high offshore towers it is increasingly important to use an individual blade adjustment or “individual pitch control” (IPC) to reduce the mechanical loads. In the IPC, relatively pronounced blade angle asymmetries are generated. Loosening of the monitoring settings in amplitude and time during the previously used monitoring methods for symmetrical blade actuations would lead to unacceptable increases in mechanical loads in specific situations or load cases.